Where valuable minerals exist in subsurface ore beds it is necessary to remove the overburden material before the ore may be mined. Because overburden removal increases costs, removal must be as efficient as possible.
Various apparatus and methods for removing overburden are known and generally comprise a semi-permanent rock crusher interconnected to conveyor systems for transporting crushed overburden material to a spoil site distal from the excavation site. Overburden is excavated from a mine face using machines such as mechanical shovels. Blasting may precede excavation. When the distance between the mine face and rock crusher is not great, the excavated overburden is deposited directly into the rock crusher by the excavating machines. However, as the mine face advances due to excavation, the distance the excavated overburden material must be transported to the rock crusher increases which requires the excavating machines traverse back and forth between the mine face and the rock crusher. Alternatively, transport vehicles such as dump trucks may be used to traverse the distance. Unfortunately, as the distance increases, efficiency decreases. To address this problem, additional transport vehicles may be employed or the rock crusher may be shut down, disassembled and moved to a position closer to the mine face and then reassembled. Shutting down a rock crusher so that it may be moved materially adds to the amount of unavoidable down time caused by foreseeable repair and maintenance. Such additional “down time” further increases costs and may make a project not economically viable.
Overburden normally consists of a layer of fertile top soil over one or more layers of rocks and the like. Modern reclamation practices encourage segregation and separate handling of the topsoil layer so that it may be replaced atop the excavated overburden material when the land is reclaimed. Unfortunately, segregation of the topsoil can be prohibitively expensive.
There is a need to increase the efficiency of overburden removal, without incurring additional costs of transport equipment and without additional downtime caused by shutting down, disassembling, moving and reassembling a rock crusher. There is also a need to reduce the cost of mine site reclamation and top soil segregation.
My invention resolves various of the aforementioned problems by providing a self-propelled, mobile sizer having an integral rock crusher and interconnected mobile conveyors for receiving, comminuting and transporting overburden material, and for depositing the overburden material at a spoil site.
My overburden removal system having a triple track mobile sizer is movable under load, follows the excavating machines as the mine face advances and remains continuously interconnected to mobile conveyor systems for transporting the excavated and crushed overburden material to the spoil site.
My system does not need to be shut down and disassembled to be moved, and is structurally configured to minimize shovel cycle times. Further, my overburden removal system and its interconnected mobile conveyors facilitate segregation of the fertile topsoil from subsurface overburden material making mine site reclamation efficient and more effective.
My invention does not reside in any one of the identified features individually but rather in the synergistic combination of all of its structures, which give rise to the functions necessarily flowing therefrom as hereinafter specified and claimed.